Sanding block



May 12, 1970 s. F. BOWEN SANDING BLOCK Filed April 1, 1968 INVENTOR.STUART F. BOWEN ATTORNEY United States Patent 3,510,991 SANDING BLOCKStuart F. Bowen, 5626 Vale Way, San Diego, Calif. 92115 Filed Apr. 1,1968, Ser. No. 717,701 Int. Cl. B24d 15/00 US. Cl. 51-372 9 ClaimsABSTRACT OF THE DISCLOSURE A sanding block for supporting a continuousloop sanding belt, which sanding block has first and second blockspositioned in the belt with adjacent ends of the block having alignedslots with inwardly inclined bottom surfaces in which opposing cammembers are positioned for being moved inwardly and expanding the blocksin an outward longitudinal direction against the sanding belt making arigid composite structure.

BACKGROUND OF THE INVENTION Sanding blocks that expand within acontinuous loop sanding belt and provide a composite sanding tool havemany useful applications, both by the handyman and in industry. Thereare several known sanding block constructions that generally comprise apair of co-planar members that are expanded longitudinally against theinner surface of the continuous loop sanding belt. At least one typesanding block employs spring means to force the blocks apart and againstthe loop sanding belt. These spring biased blocks have the disadvantageof not providing a rigid internal structure for the sanding belt. Ratherthe two blocks are capable of being moved towards each other against thespring force during sanding, which loosens the belt. Other means areoften used to expand the blocks, such as wedges being driven between theblocks and the use of a bolt that is aligned between the blocks and isforced outwardly to move one block in a direction away from the otherblock. These other known structures have the disadvantage of utilizing ameans that when one placed in position is difiicult to remove, as isnecessary when a new sanding belt is placed on the sanding belt block.In others of the known means, there is no side uniformity ofdisplacement of one block relative to the other block. This allows sidesway with a greater tension being applied to one side of the continuousloop sanding belt than is applied to the other side.

It is thus advantageous to have a sanding block for supporting acontinuous loop sanding belt that is rigid and strong in construction,is capable of expanding or forcing one block in a direction away fromthe other block in an'efficient, uniform and positive manner in whichthe displacement on both sides of the respective blocks is held uniformand which block is quick and easy to operate, is inexpensive toconstruct, and is rigid and durable in construction.

SUMMARY OF THE INVENTION The embodiments of the sanding block of thisinven tion generally comprise first and second substantially rectangularblocks that, in the operative position, are in 3,510,991 Patented May12, 1970 longitudinal, co-planer alignment. The blocks are generallyconstructed of solid material with one of the blocks having alogitudinal length that is substantially greater than the other block.The facing or adjacent ends of each of the blocks have a longitudinalslot extending from one side of the ends to the other. The slots areformed with upper and lower lips that define a slot volume alignedthrough the mid-point of each block in a direction normal to thelongitudinal axis of the blocks. The bottom surfaces of each of theslots in each of the blocks are inclined inwardly in a direction towardthe end surfaces and at a slight angle to a plane normal to thelongitudinal axis of the blocks. Thus the adjacent slots in the facingends of the blocks have similar inclined surfaces.

Positioned in the slots at each adjoining end are identical cam membershaving a thickness corresponding to the spacing between the sides of theslots and having opposite inclined surfaces that mate with the aforesaidinclined slot surfaces. A bolt having oppositely wound spiral threadsengage threads in the respective cam members. Upon turning the bolt, thecam members are drawn together and up the inclined surfaces of theslots, forcing the block members in opposite directions away from eachother and thereby expanding against the inner surfaces the continuousloop sanding belt. This tightens the belt in such a manner that thecurved end surface of one of the blocks provides a curved sandingsurface and on the other end of the block a sanding surface with sharpsquare edges.

It is therefore an object of this invention to provide a new andimproved sanding block.

It is another object of this invention to provide a new and improvedsanding block for supporting a continuous loop sanding belt.

It is another object of this invention to provide a new and improvedsanding block for supporting a continuous loop sanding belt that isrigid in construction and final assembly, is easy and inexpensive tomanufacture, and is easily assembled and disassembled.

It is another object of this invention to provide a new and improvedsanding block for supporting a continuous loop sanding belt thatprovides uniform and rigid movement of each side of the opposing blockmembers, one relative to the other, to provide uniform expansivepressure across the entire width of the sanding belt in the longitudinaldirection.

These and other objects of my invention will become more apparent upon areading of the following detailed specification and an examination ofthe drawings in which like reference numerals identify like partsthroughout the views of the drawings and in which:

FIG. 1 is a perspective view of an embodiment of this invention in theoperative condition with the continuous loop sanding belt mountedthereon.

FIG. 2 is an exploded perspective view of the operative mechanism of oneof the embodiments of my invention.

FIG. 3 is an exploded view of another operating mechanism for use in myinvention.

Referring now to FIGS. 1 and 2, the embodiments of the sanding blockcomprises a first block 12 and a second block 10. The two blocks have asubstantially rectangular shape with flat co-planar surfaceslongitudinally arranged in the operative position. As may be seen, thesecond block is substantially longer than the first block 12 with eachblock having a solid construction. The blocks may be made of wood,plastic, or any other suitable material and have finger grippingrecesses 52 on the sides thereof for facilitating use.

A continuous loop sanding belt 26 may have any suitable surface, such aswould comprise a finishing sanding belt, a rough cut sanding belt, orabrasion belts. The continuous loop sanding belt encloses the first andsecond blocks in the longitudinal direction in the manner illustratedand upon lengthwise expansion or movement of the blocks 10 and 12, theblocks move out against the belt holding the entire device in arigidcombined structure. The front of block 12 has a curved surface 48and the rear edge of the block 10 has sharp square edges. The belt 26has a width that exactly conforms with the width of the blocks 10 and12. It may thus be understood that the sanding block has particularadvantageous uses in being able to sand curving surfaces with the curvedend and to sand corners and edges with the sharp end edges 50. Furtherby utilizing a quick and easy operating mech anism for expanding the twoblocks, the sanding 'belt 26 may be suitably rotated on the sandingblock structure to provide new sanding edge surfaces at the respectiveends of blocks 10 and 12.

The adjacent or opposing faces of blocks 10 and 12 have slots 14 and 16that pass from one side of the block to the other in the centeredportion thereof. Each of the slots have end projections 44 and 46 with agiven lateral space therebetween and have bottom surfaces that areinclined inwardly from each side forming inclined surfaces 18, 19, 20and 21. A pair of cam members 22 and 24 have thicknesses substantiallycorresponding to the distances between the projection members 44 and 46and thus fit therebetween. The cam members each have inclined surfaces30 and 32 that rest against the respective inclined surfaces in theslots 14 and 16. The cam members 22 and 24 are interconnected by bolt 28that has oppositely spiraled threads 34 and 36 with a centercircumferential groove 38 that is aligned with the mid-point of therespective blocks 10 and 12. The head of the bolt 28 projects outthrough one side of the cam members 22 thus providing means for turningthe bolt in the normal manner. It may be seen that by turning the bolt28, the cam members 22 and 24 are either pulled toward each other or aremoved away from each other in equal amounts. A U-shaped wire slip 40fits into groove 38 with the ends projecting into the openings 42 in thebottom of the slot 14 of block 10 and holds the bolt member 28 and camblocks 22 and 24 in retained, aligned position during assembly.

In operation, the cam members 22 and 24 are inserted into the slot 14and wire slip 40 is passed over groove 38 with the ends of the slipbeing inserted into openings 42. The first block 12 is then slidablypositioned over the projecting sides of earns 22 and 24 and thecontinuous loop sanding belt 26 is placed around the longitudinal outersurfaces of the blocks. The bolt 28 is then rotated in the normal mannerby a screwdriver or like tool drawing cam members 22 and 24 together andup the inclined surfaces 18, 19, 20 and 21 forcing outward movement ofthe first and second blocks in a direction away from each other andtensioning belt 26. In this assembly the blocks 10 and 12 are originallypositioned in an aligned co-planar relationship and the cam members 22and 24, being identical, create an equal force on each side of the blockthat holds the entire structure in a rigid and supported alignment. Theblock is disassembled by reverse application of the previously describedprocedure allowing the sanding belt to be either removed or changed inposition on the sanding block.

Referring to FIG. 3, the structure of the sanding block in thisembodiment is substantially the same as that described relative to FIGS.1 and 2, with the difference being that slots 60 and 82 have differentmeans for holding the bolt 80 and cam members 72 and 74 in position. Thesecond block 56, corresponding to block 10 in FIG. 2, has forwardprojecting portions 66 and 68 with a slot 70 therebetween. The firstblock 58 has a recessed vertical opening 86 for receiving theprojections 66 and 68. Bolt has a wide circumferential groove 78 thatfits in the slot 70 with the edges of the groove 78 substantiallyabutting the sides 77 of the projections 66 and 68. Accordingly theprojections 66 and 68 and slot 70 function to hold the bolt 80 and thecam members 72 and 74 in the desired oriented position relative to theslots 60 and 82 and the inclined surfaces 62 and 84. The operation ofthe block illustrated in FIG. 3 is the same as that previously describedrelative to FIG. 2. The cam members 72 and 74 and 22 and 24 may be madeof metal, plastic, or any other suitable rigid material.

Other objects, advantages, and modifications of my invention will beapparent to those skilled in the art, all of which I desire to coverWithin the scope of the attached claims.

Having thus described my invention, I now claim:

1. A sanding block for supporting a continuous loop sanding beltcomprising,

first and second blocks,

said blocks in the operative position being in longitudinal co-planaralignment.

the adjacent end surfaces of each of said blocks having aligned slotswith inwardly inclined bottom surfaces extending from each side of saidblocks,

a pair of opposing cam members having inclined side surfaces for fittingin said slots and resting against said inclined bottom surfaces of saidslots,

and means interconnecting said cam members for moving said cam memberstoward each other and up said inclined surfaces of said slots forcingsaid blocks in a direction away from each other.

2. A sanding block for supporting a continuous loop sanding belt asclaimed in claim 1 in which,

said inclined bottom surfaces in each of said slots comprising a pair ofsurfaces that incline in a direction toward said end surfaces.

3. A sanding block for supporting a continuous loop sanding belt asclaimed in claim 1 in which,

said interconnecting means comprising a connecting bolt havingoppositely spiraled threads on each end that threadably engage threadsin said cam members.

4. A sanding block for supporting a continuous loop sanding belt asclaimed in claim 3 in which,

said bolt having a circumferential recessed portion adjacent the alignedcenters of said slots,

and holding means on at least one of said blocks for fitting into saidrecessed portion and holding said bolt 7 in a centered position relativeto said slots.

5. A sanding block for supporting a continuous loop sanding belt asclaimed in claim 4 in which,

said circumferential recessed portion comprising a groove,

and said holding means comprising a U-shaped member for fitting in saidgroove with the ends of said U- shaped member projecting into holes inthe end of one of said blocks.

6. A sanding block for supporting a continuous loop sanding belt asclaimed in claim 4 in Which,

said circumferential recessed portion comprising a groove,

and said holding means comprising a portion of said one of said blocksthat extends longitudinally from said end surface and has a recess withside walls that fit over the recessed portion of said groove.

7. A sanding block for supporting a continuous loop sanding belt asclaimed in claim 1 in which,

the opposite end of said first block having a curved surface,

and the opposite end of said second block having a square shape withsharp edges.

8. A sanding block for supporting a continuous loop the longitudinaldirection to expand against said sandsanding belt as claimed in claim 1in which, ing belt forming a rigid structure.

both of said blocks having a solid construction,

and said second block having a substantially greater References Cited{:lugth in the longitudinal direction than said first 5 UNITED STATESPATENTS ock.

9. A sanding block for supporting a continuous loop 21531588 11/1950Stucker 51380 sanding belt as claimed in claim 1 in which, $06310811/1962 Bell et 51 372 a continuous loop sandin belt,

said first and second bloc l s being held in the operative OTHELLSIMPSON Pnmary Exammer position by said sanding belt, 10 U S C1 X R andsaid cam members in cooperation with said interconnecting means movingsaid blocks outwardly in 51391

